It is not surprising Darth Vader is based on samurai armor - what's surprising is that it took so long for anyone to take advantage of that for a cool toy.
(Well, an official toy: customizer
Sillof famously did a whole series based on that idea, but we're talking about things that normal humans could buy with normal human money.)
In 2014, Bandai's "Tamashii Nations" brand kicked off a new line, Movie Realization, which takes existing movie characters (so far only Star Wars, but there's nothing saying other films couldn't get involved eventually) and reimagines them in the Japanese feudal era. Clearly they began with Darth Vader, because every new endeavor is at least somewhat a gamble, and if you're only going to get one shot at something, you want to do the best you can just in case.
The translation really does work well. The figure was designed
by Takayuki Takeya and sculpted by Junichi Taniguchi, and if you lived in a world unaware of Darth Vader, you would easily think this was some accurate historical replica. For instance, look at his face mask: it retains the triangular shape for the nose seen on the real mask, though here it's been reimagined as a stylized shouting mouth, complete with teeth inside there.
While the outer helmet is gloss black, the rest of the outfit is matte - a choice that is apparently true to the real Vader costume. Below the chin, the sculpt definitely leans more toward the "samurai" side
than the "Vader" side, with the only unmistakably Star Wars parts being the colored designs on his belly (standing in for Vader's chest panel) and the golden discs on his haidate - not that those are directly from the movie costume, but they're Imperial insignia, just like the maedate crest on his forehead. Other than those, the parallels are mostly subtle: for instance, the vertical lines on his suneate and han kote (and the haidate again) call to mind Vader's quilted undersuit, though going full "squares" on the sode may be too much of a good thing. The collar armor between his dō and yodare-kake is silver and black, just like Vader's mantle. There's nothing particularly movie-ish about the breastplate, just a nicely intricate sculpt.
The figure includes your choice of eight hands: two fists, two "holding," two with the fingers splayed, and two with just
the thumb and index finger out - in other words, a pair to perform Force chokes! He's armed with a katana, logically, and given the idea of the Movie Realization line, you can probably guess what it looks like - the blade is translucent red, and the hilt has raised black ridges, just like Vader's lightsaber. Fun! He can hold it in the intended hands, and there's also a second hilt (with no blade) that can clip onto his waist.
We get great articulation, too.
The figure moves at the neck, shoulders, elbows, wrists, waist, hips, knees, and ankles. There's also a balljoint poking out of the center of his back that plugs into the cape to hold it in place, but still allow it to move around. There's some limitation to the joints - the uwa-obi keeps the legs from rising up too far, and his legs are so chunky that the double-knees still only manage to get about a 90° angle - but with nearly everything being a balljoint or swivel/hinge, you can do lots with him.
This figure was released in December 2014, but it was so popular that it saw a re-release two years later. Right in between those two, there was a different figure, "Death Star Armor" Darth Vader, which looks a bit better in the body, but has a totally stupid crest that's a giant icon of the Death Star. If it were closer in size to the one here, we'd be recommending that figure over this one, but as it is, no, this is the version to get. Samurai Darth Vader kicked off an entire line of action figures (two if you count Manga Realization separately), but none of the other characters make as much sense as he does. It may not fit with your normal Star Wars figures, but the design is cool enough to make him worth it. Maybe on Singles Day, but still worth it.